I'm getting my lawyer too... might actually start a gofundme page to get the book I paid for. If he wrote the book over 1,000 pages when he knew he needed it to be only 500 odd pages, there's a simple solution. Reduce the spacing in between the lines and/or reduce the font size. He could also do a search on "that", "which" and remove them as they are often not required. He could also reduce the number of pages required by replacing Commodore with just the chicken head symbol and instead of writing Amiga it could be shortened to Miga, even.
Seriously this guy needs to write succinctly anyway... he knew what the Kickstarter was for, he would be seriously penalised if he wrote a 4000 word essay and the requirement was to only write a 2000 word essay. He would have failed at university! I guess he has all of our money now and thinks he can do whatever he wants. Write the book like he said he would, a complete book, not half a book and if you can't fit it in, make the spacing in between the lines smaller and or the font size smaller and take some of these other serious suggestions on board!